A simple way to convert this model for use with N Scale:
Remove the side frame truck detail. Sand down as appropriate.
Attach two Micro-trains (1173) Buckeye trucks back to back, onto the cleared truck frame. Repeat with second truck. Four Micro-trains 1173 total.
Paint as desired.
Continue Model assembly.
A more complicated option that preserves the original truck include drilling a hole from one side frame to the other and inserting an axle. Gauging a set of wheels to N Scale Standard on that axle. Be sure to use an Insulated wheel with this option. Repeat for all 12 axles.